1. Field of the Invention
The present invention relates to an image pickup unit including an optical element, which is provided on an optical axis, and an image sensor, which is retained by a retaining member, and an image pickup apparatus including the image pickup unit.
2. Description of the Related Art
An image pickup apparatus, such as a digital camera, which converts an object image into an electric signal, receives a light flux of the object image on an image sensor. Furthermore, the image pickup apparatus converts the electric signal, which is output from the image sensor, into image data. In addition, the image pickup apparatus records the resulting image data on a recording medium, such as a memory card. As the image sensor, a charge-coupled device (CCD) sensor or a complementary metal oxide semiconductor (CMOS) sensor is used.
The image pickup apparatus like this includes an optical low-pass filter and an infrared cut filter, which are provided on the object side of the image sensor. If any foreign matters, such as dusts, adhere to the surface of the filter, the adhered matter may appear on a captured image. In this case, the image quality may degrade.
In particular, in a digital single lens reflex camera including an interchangeable lens unit, mechanical operational units, such as a shutter or a quick-return mirror, are provided in the vicinity of the image sensor. Accordingly, foreign matters, such as dusts, which have come out from the operation units, may adhere to the surface of the image sensor or the filter. In addition, during an operation for changing the lens unit, foreign matters, such as dusts, may enter into the camera body via an opening of a lens mount. In this case, the intruded foreign matters may adhere to the surface of the image sensor or the filter.
In order to prevent the above-described phenomena, Japanese Patent Application Laid-Open No. 2008-26564 discusses a method for removing foreign matters, such as dusts, which have adhered to the surface of an optical element, which is provided on the object side of an image sensor, by causing the optical element to vibrate by using a piezoelectric element.
More specifically, the method discussed in Japanese Patent Application Laid-Open No. 2008-26564 includes a vibration unit configured to vibrate the optical element, which is provided on an optical axis, in a wave-like manner. Furthermore, the above-described conventional method removes dusts or other foreign matters that have adhered to the surface of the optical element by causing the optical element to resonate in two or more vibration modes.
However, in the method discussed in Japanese Patent Application Laid-Open No. 2008-26564, an image sensor retaining member, which is supported by a mirror box, is provided separately from an optical element retaining member, which is configured to support an optical element including the vibration unit. Accordingly, in this case, the number of necessary parts may become large. In addition, in this case, the number of worker-hours for assembling the camera may become also large.
In addition, because an optical element unit and an image sensor unit are sealed by a two-sided adhesive rubber sheet, it is difficult to peel off the two-sided adhesive rubber sheet at the time of rework.